... simple test for transparency to RF at 1.575 GHz is to place the GPS antenna inside then outside the plastic box under consideration then (given the right module!) read the difference in signal stength (my JRC OEM modules in one mode do this trick with ease and the SS value measured is output relative in deciBels) ... Second test: Place the GPS antenna in the final position within the plastic box under consideration in the *same* proximity to the plastic box's top surface and again measure the signal strength. Proximity of the antenna to the platic "cover" will affect antenna pattern directly and therefore affect indirectly the antenna's utltimate gain in the desired direction. (I think I saw a previous post along the same lines but no reference to the box's plastic affecting the antenna pattern when in close proximity ...) RF Jim ----- Original Message ----- From: "Russell McMahon" To: Sent: Friday, August 02, 2002 1:56 AM Subject: Re: [OT]: GPS Case design * snip * > > A simple test for transparency to RF at 2.4 GHz is to place a piece in a (n > operating :-) ) microwave oven. Any heating suggests you should find > another plastic. While this is not necessarily representative of how the > material will act at other frequencies it often gives a fair indication. > (Note that water has an absorption line at ~2.4 GHz which is why they use > that frequency. ) > > Testing for a minute or so is probably worthwhile. Having some other "load" > in the oven at the same time is necessary if you value your magnetron. > > > RM > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.